Geometrical instrument



May 6, 1924. 1,492,893

- J. A. NELL v GEOMETRICAL INSTRUMENT Filed Aug. 12, 1920 2 Sheets-Sheet 1 Ava k Jn mufoz CAM Q1 Lu d Patented May 6, 1924 UNITE ST JAMES A. NELL, OF NEW BRITAIN, CONNECTICUT.

GEOMETRICAL INSTRUMEN '1.

Application filed August1 2, 1920. Serial No. 403,063.

To all whom it may concern:

Be it known that I, JAMEs A. NELL, a citizen of the United States, and aresident of New Britain, in the county of Hartford and State of Connecticut, have invented certain new and useful Improvements in Geometrical Instruments; and I do hereby declare the following to be a full, clear, and exact description, of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to improvements in geometrical instruments and more particularly to an improved device for use in drafting,'one object of the invention being to provide a simple, substantial-and efficient instrument, the use of which will facilitate the accurate drawing of lines bearing angular or other relation to eachother and obviate the loss of time and danger of inaccuracy incident to the use of two or more instruments which must be repeatedly and alternately used and reused.

With these and other objects in view, the

invention consists in certain novel features and combinations and arrangements of parts as hereinafter set forth and pointed out in the claims.

In the accompanying drawings; Figure 1 is a plan view of a drafting instrument illustrating an embodiment of my invention; Figure 2 is a separate view of the adjustable tongue or arm; Figure 3 is a'sectional-view; Figure 3 is a detail view of the bolt 27; and Figures 4 and 5 are diagrammatical views, illustrating some of the uses to which the instrument may be applied.

In the preferred construction of the instrument, as shown at 1 in the drawings, I employ a rectangular frame preferably of metal.

It will be observed that the instrument comprises two longitudinal members 13, 14, and two end members 15, 15,said members being so proportioned and assembled as to form a rectangular frame and the member 14 is provided with a rectangular opening 16, which is equal in length to thatof the space within the frame and of a predetermined width. It will be observed that the member 14 forms, in effect, a sub-frame.

All of the members 13, 14 and 15, are provided at their outer edges with scales 17 graduated in inches and fractions thereof and said members are also provided at their inner edges with scales 18 which are likewise graduated The inner edges 'ofcthe 7 parts of the member '14 of thedevice are graduated in'inches and fractions thereof as indicated at 1920, and those portions of the device which form the ends of the rectangular space 16 are graduated in fractions of an inch as indicated at 21', 21.-

Intermediate portions of the frame mem bers13 and 15 are provided with scales 22,

22, 22, graduated in degrees of acircleor rather, a semi-clrcle, and-those corner portions of the frame which are at respective ends of the sub-frame member 14 are pro vided with sockets 23, 24 to permlt the or arm 25L A portion-of the bodyfof the bolt is flattened,-

portion; to receive thumb nut 28,

thereby forming shoulders 29 and a disk I 30 is mounted on-the flattened portion of' the bolt, said disk being provided with a pintle 31 to enter one'of the sockets 24in the r a v, v, the flattened portion of thebolt 27 and-;be tween the disks 30 and 32 one end portion of the tongue or arm 25 is located, said arm being provided with a suitable hole for the free passage of the bolt 27. By means of the connecting devices above described, the tongue or arm 25 may be removably attached to the frame at either lower corner thereof and can be held at any desired adjustment relatively ,to the frame, by frictional engagement between the disks 3032 when the thumb nut 28 is tightened.

The instrument is used in conjunction with the T square in a similar manner as the ordinary triangle is used as regards movement over the drawing board and it will be obvious that either edge of any member of the instrument may be used for guiding the pen or pencil in drawing a line. The members should be about .020 of an inch less than one inch wher the members are rated at one inch, making it admirable for drawing lines one inch apart by simply running the pencil along each edge of the member,the .020 of Another disk 32" islocated on an inch being an allowance for the thickness of the pencil mark and also enabling the user to see or sight a line where one line has already been drawn. WVhen lines at right angles are required they may be drawn at one setting within the capacity of the instrument. For example let it be assumed that a figure 2 by 3 is'to be drawn. To accomplish this, place the instrument against the tongue of the T square l select a position for the figure,,then place the point of the pencil at a place corresponding to 2" on the inner side of the left hand member; draw a line down to the corner B; then without removing the pencil, draw a horizontal line along the edge of the'lower member until the distance of 3 is reached. The two lines will form a letter L. Then move the instrument over the board bringing the graduations of the upper member corresponding to 3 to the line A Figure 4 and the graduations of the member at the right to correspond to 2 on the line C Figure 5; then draw line from A to D and from D to C completing the figure. The outside of the instrument may be used in a similar manner.

Assuming the line L L Figure 5 represents the limit of the drawing board and a line is required from the line E, E,-it is obvious that the member 13 of the instrument cannot be brought down to be used for drawing it without crowding the tongue of the T square off the board. To overcome this the lower member or sub-frame 14 is provided, and, assuming that the open space 16 in the sub-frame is a, wide and the bars are f wide, to draw a line 1} from the line E, E, place the instrument so that the line E E can be read "i g from the inner bar of the sub-frame as shown and draw a line as at F, F, which will be from E, E.

Various changes might be made in the structural details of my invention without departing from the spirit thereof or limiting its scope and hence I do not wish to restrict myself to the precise details herein set forth.

Having fully described my invention what I claim as new and desire to secure by Letters-Patent, is

1. A drafting instrument comprising a rectangular frame, three members of which are provided with scales graduated in degrees of a circle, and a tongue attachable to a corner of said frame and adapted to be made to register with one or another of said degree graduations.

2. A drafting instrument comprising a rectangular frame, three members of which are provided with scales graduated in degrees of a circle, a tongue attachable to a corner of said frame and adapted to be made to register with one or another of said degree graduations, and frictional devices connected with said tongue and removably attached to a corner of said frame.

3. A drafting instrument comprising an open rectangular frame, each member of which is provided at its outer and inner edges with graduations of linear measurement, one member of said frame having a rectangular opening equal in length to the distance between the frame members which meet the member having the opening and having graduations of linear measurement at both sides and both ends of said rectangular opening.

In testimony whereof, I have signed this specification in the presence of two subscribing witnesses.

JAMES A. NELL. Witnesses:

WILLIAM J. QUIGLEY, (also. A. QUIGLEY. 

